What is meant by the term linkage disequilibrium?

Linkage disequilibrium refers to a nonrandom association of alleles at different loci within a population. This means that certain alleles are found together more frequently than would be expected based solely on their individual frequencies. For example, if two genes are located close to each other on a chromosome, they may not segregate independently during meiosis, resulting in specific combinations of alleles that are inherited together.

This concept is particularly important in genetics because it can provide insights into population structure, evolutionary processes, and the mapping of genes related to diseases. It contrasts with linkage equilibrium, where alleles at different loci are randomly assorted. Understanding linkage disequilibrium is crucial for genetic studies, especially in the context of association studies that seek to identify genetic variants linked to phenotypic traits or health conditions.